(CNN) -- Researchers with a Malaysian university said they have uncovered evidence of an iron industry that dates to the 3rd Century, A.D., and proves that ancient civilizations in Southeast Asia were more advanced than once thought.

The archaeologists from the Universiti Sains Malaysia found the remains of an iron smelting site, tools to pump oxygen into the iron smelting process, rooftops of buildings, beads and pots, said Mokhtar Saidan, a professor and leader of the team.

The discovery was made after a month of excavation at Lembah Bujang, a historical site in Malaysia.

"This is the first discovery of the earliest iron industry in Lembah Bujang and has been dated conclusively. This date also adds on to the facts and data on the early history of Southeast Asia," he said.

He said coal from the site was sent to a laboratory in Florida that said elements in the coal dated to the 3rd Century.

The professor said the discovery confirms that human civilization in the area was more advanced than thought and the site probably was a place for exporting iron in the 3rd Century.